This study is a Phase 2 pilot study to characterize and examine the pharmacokinetics and efficacy profile of Chronocort® in adults with congenital adrenal hyperplasia (CAH). It is designed as a two-part, single cohort, open label, multiple dose Phase 2 pilot study to: (Part A) characterize and examine the pharmacokinetics (PK) and disease bio-marker behavior following short-term dosing with Chronocort®; and to (Part B) examine the disease control after six months dose titration with Chronocort® in adults with CAH.